davis



.T0 all whom; it may concern.:y

j UNVIEIA STATES PATENT OFFICE.

' JAMES `Is.` parvis,- oFwAsHINGToN, DISTRICT oF COLUMBIA.

GAS-'CH Eea-'FOR `4`(murmures.4

SPIEICIFIC'ATION forming part'of' Letters Patent No. 318,093, dated May' 1.9. 1885.

i Application filed December 23; 18S-f. (No model.) l

vBe it knownthat I, JAMES B. DAVIS, resid- 'ing at Washington, in the District of Colunr Y bia, have invented certain new anduseful Improvements inG as-Clrecks for Breech'-Loadi ng Ordnance, of which the following is a specification, reference being had therein to the" accompanying drawings. f

This .invention relates to gas checks 'for breech-loading ordnance; and vit consists in certain improvements, as hereinafter set forth and claimed.

The object of the invention iste produce a gas-check which will operate perfectly to close the breech of breech-loading cannon against gas escape, and which will. not set77 in ex# panded position.

Prior to my invention gas checks somel what similar to mine had `been used, bntthe view of the gascheek rings were of soft metal, and it frequently became necessaryto pass a rod into the gun from the muzzle in order firing.`

to start the breech after- My invention is particularly intended as an improvement on Patent No. 301,220, of July 1, 1884.-

In the drawings, Figure l is a longitudinal section of a portion of the breech-plug of a gun with mygascheck applied. Fig. 2'i's a' face .view of one of the gas-rings. H Fig-.3 is a in position in the breech ofagun. e

A.indicates the breech-plug, which is usually provided vwith ajmutilated Vscrew-thread -33 to secure it inthe breech of the gun A2. B istlre lso-called mushroom the head vII forming the front of the breech-plug. The stein bf` of the mushroom is screw-threaded,

` and lock-nuts C C' on said stem bear against the spring D, which rests against the shoulder a in the plug,l serving to draw the mushroom towardthe rear of the `plugjwith'a springpressure.

E E `are steel plates having central holes, e, for Vthe passageof the mushroom-stem, and* 'being concaved between the central stem and,

the outer edges. The edges f f' ofthe plates 4E E are brought nearly to knne-euges.v The periphery of each plate is a `cylinder whichl will just enter its seat in the gun. In the annnlar space between the plates E E' there is :L

'bag or cushion, K, preferably of canvas, said bag being filled with a slightly-compressible i brous'material, as asbestus and tallow. The plates E E and the packing between them can be removed by unscrewing the nuts'and r'ei moving the mushroom.

I find it more convenient in manufacture to make the rings E E separate from the plug and mushroom' than toA turn them up solid with those parts. v

When la gun having this gas-check in position is fired, the backward pressure of ,the

powder-gas on the mushroom expands the bag and its filling radially, which also expands the knife-edges oft-he rings atfff, making a tight joint.

'A compound plate of brass and tin or brass vand copper has been used iu the location of one of my plates E E', but said plate differed lfrom mine in material, in structure, and in function.

VI clain 1. In combination with the breech-plug 4 and mushroom head, a pair of steel rings surrounding the stem of saidl head, said rings having annular concave spaces in their proximate faces, and a' textile bag filled with fibrous material between said plates, substantially'as described.

'2. The combination,.with the breech-plug of a heavy gun, of a' mushroom-head secured.

thereto by nuts on the mushroom-spindle, a spring pressing the mushroom backward, a pair -of steel rings, E E', between the head and plug, and an elastic cushion between the steelrings,V all substantially as shown and described. y;

' In testimony whereof I affix my signature in` presence oftwo witnesses.

' JAMESB.' DAVIS.

.IVitnessesz Y W. A. BARTLETT, 5

.T HARRY STUART, 

